OK, so I'm probably just getting old and stuff, but for the life of me, I can't find the Reply button in the Private Message section!!!
Try with the quote link, unnecessary text may be deleted afterwards. Or just send a new message, clicking on board's member profile or using his exact nickname as recipient username when using "send new message" in your own profile.
Whew! It's not just me. I thought I was going senile. Really need a reply button added.